1. Field of the Invention
The present invention relates to an anchor which is inserted into a bone for the purpose of receiving a post and core. The anchor threads to bone tissue, and provides structure for secure mounting of the post and core within the mouth.
2. Description of the Prior Art
Replacement or artificial teeth have become available as an answer to the loss of original teeth. Natural or original teeth are secured in place by roots, which cooperate with the body tissue. When a natural or original tooth is lost, the root is usually also lost. Secure attachment for the new tooth must be provided which will hold and support the tooth securely enough to resist forces generated in biting and chewing.
In contemporary practice, a socket or receptacle for receiving the tooth is placed in the jaw bone, and a post and core assembly is set into the receptacle. The receptacle must cooperate with the natural body into which the new tooth is set. Usually, underlying bone tissue is drilled to accept an anchor. The anchor is threaded into the bone, the anchor frequently serving as its own tap to form threads in the bone.
The receptacle normally secures the post and core or healing screw in one of two ways. For temporary, removable securement, the healing screw is threaded into the receptacle. For permanent securement, the hexagonal shank of the post engages a cooperating bore formed in the anchor, and the engagement is cemented into place.
Normally, the anchor is provided with self-tapping threads, and engages the bone by being screwed into a hole bored into the bone. The self-tapping threads carve cooperating threads into the unthreaded hole in the bone. In all known prior art threading schemes, the final diameter of the threads formed in the bone is achieved by the first convolutions of the self-tapping threads of the anchor.
U.S. Pat. No. 4,863,383, issued to Hans L. Grafelmann on Sep. 5, 1989, illustrates an implant having an anchor which has a tapered body. Unlike the present invention, the screw threads are of constant outer diameter throughout the length of the anchor. This is in contrast to the present invention, wherein threads are of progressively increasing outer diameter.
Grafelmann also provides the upper end of his anchor with an opening for receiving a post, which opening has both a hexagonal portion and also female threading. The threading is located below the hexagonal portion. By contrast, the present invention locates both a hexagonally walled opening and female threading at the same level along the length of the anchor, in a superimposed manner.
U.S. Pat. No. 5,078,607, issued to Gerald A. Niznick on Jan. 7, 1992, U.S. Pat. No. 5,246,369, issued to Francis Poulmaire on Sep. 21, 1993, and U.S. Pat. No. 5,312,256, issued to Gerard Scortecci on May 17, 1994, further illustrate anchored dental implants. In all cases, external threading engaging bone tissue is of constant diameter, unlike that of the present invention. Also unlike the present invention, these inventions lack female threading superimposed on a hexagonally walled cavity, for receiving a post of a subsequently installed component.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.